• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.402-405
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• 2005

Such press-forming process are the used machine ability and the characteristic, used material, tile accuracy of the part, condition of a process are considered the designed. In order to estimate in automotive sheet forming processes used AutoForm software. A through in simulation result comparison with experimentation result, it was possible to know that much the same estimated spring-back through a forming analysis. By making apply this to an industrial site the productivity improvement and cost reduction etc. effect able was predicted.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.50-58
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• 1994

To examine the residual stress field resulting from stamping process for the lower control arm of a car, the explicit finite element analysis is performed for the stamping process by way of the ABAQUS Explicit. The residual stress is obtained in terms of the Von Mises stress and other parameters such as equivalent plastic strain, the change of blank thickness, the final configuration of the blank and the spring back effect are also considered. Moreover, discussed is the convergence of the explicit FEM versus the punch sped and the element discretization

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.58-64
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• 2008

The cutting process of materials is accompanied with the elastic and plastic deformation due to chucking forces in the boring process of thin holes on the turning. Upon removal of chucking forces at the end of process, the original shape is remained in the plastic deformation; on the other hand, it is modified in the elastic deformation due to spring back. Fixing materials by chucks on the turning has influence on roundness because the process is conducted with unbalanced distribution load induced from the fixing of three jaws. Moreover, the amount of spring back depends on the magnitude of fixing forces. We studied the change of roundness according to fixing forces as well as the method to reduce the influence of chucking forces.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.493-496
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• 2008

The residual stress generated in the boron steel blank formed via hot press forming process was predicted by JMatPro, a material property modeler, and Abaqus. The numerical predictions were compared by the experimental measurements obtained by the instrumented indentation. Both the predicted and measured principal stresses monitored at the outer surface of central bending position were qualitatively in good agreement. It was concluded that the residual stresses generated from hot forming process is not negligible as it has been generally assumed, although the spring back deformation is quite small. This should be specially considered from the part design stage since the tensile nature of the residual stress exhibited on the surface may lead to the stress corrosion cracking.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.1
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• pp.1-6
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• 2009

The optimum design of back pressure chamber is one of the most important factors in designing scroll compressors because it has a great influence on the efficiency and other design parameters. The design process can be divided into 2 parts. One is obtaining the optimum pressure of the chamber and keeping it in constant value. The other is finding out the minimum inflow rate of medium with which back pressure chamber is filled. In this study we are focused on the first step. At first we added a simple structure that can change back pressure without reassembling compressor. It makes possible to obtaining optimum back pressure. Then we designed an equipment that the back pressure control valve assembly could be independently tested with. Spring was redesigned to decrease stiffness variation. Also sealing mechanism of back pressure control valve was improved to more effective way. As a result, it was verified that in a real mode test back pressure variation could be retained in 2.3% with discharge pressure and operating frequency varied. In addition the integrated structure of back pressure control valve is expected to contribute to effective manufacturing process.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.410-415
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• 2007

The optimization of back pressure chamber is one of the most important factors in designing scroll compressors, because it has a great influence on the efficiencies and other design parameters. The design process can be divided into 2 parts. One is obtaining the optimum pressure of the chamber and keeping it in constant value. And the other is finding out the minimum inflow rate of medium with which back pressure chamber is filled. In this study we are focused on the first step. At first we added a simple structure that could change back pressure without reassembling compressor. It makes the optimum back pressure be obtained. And then we devised an equipment that the back pressure control valve assembly could be independently tested with. A spring was redesigned to decrease stiffness variation. And sealing mechanism of back pressure control valve was improved to more effective way. As a result it was verified in a real mode test that back pressure variation could be stabilized within 2.3% when discharge pressure and operating frequency varied. And the integrated structure of back pressure control valve is expected to contribute to an effective manufacturing process.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.1
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• pp.20-32
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• 1995

Springs for vehicle suspension control the vibration of a car and influence on the ridability, safety, and life of a car. In the paper, the computer aided design program has been developed, which design the leaf spring shape from the given specifications using basic theory and the expert's knowledge, and the design results are checked by the analysis theory in order to increase the accuracy, and feed back to the design input. For the purpose of easy use, this program consists of pull-down menu and interactive input mode. To prove the effectiveness of this program. two springs, of which one is symmetric, other asymmetric, are designed and analyzed, and the outputs are compared to the experiments. Considering the tolerance of the given specifications, the results are good.

• Transactions of Materials Processing
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• v.15 no.9 s.90
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• pp.660-666
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• 2006

This study examined the mechanical properties and bending formability evaluation of spring strip materials(SK5 CSPH, STS 301 CSP-EH, C7701-H). The hardness test and tensile test were performed at room temperature($20^{\circ}C$) for mechanical properties. The U-bending test were carried out at various conditions of punch corner radius(Rp), ratio of punch comer radius/thickness(Rp/t) and ratio of clearance/thickness(Rp/t) and ratio of clearance/thickness(C/t) for bending formability evaluation.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.57-63
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• 1999

A thin metal plate such as detent spring has the shape deformation due to the phenomenon of spring back after press machining and heat treatment process. This requires the correction of spring shape and force in final inspection process. To do correction of the shape deformation the impact force is manually applied to the bended part of detent spring after measuring the shape deformation and spring force. To develop the automatic spring force correction system, applied force of occurring plastic deformation must be derived from the experimental method. But frequent change of spring shape and material makes it difficult to accomplish the experimental method to be applied. This paper describes the analytical method for detent spring force correction system is to be substituted for the experimental method. FEM(Finite Element Method) is used to find the boundary value between elastic and plastic deformation in the analytical method. To confirm the validity of the analytical method, the result of two methods is compared each other at various applied force conditions. It shows that the simulation result of the analytical method is consistent with the result of the experimental method within the error bound ${\pm}$5%. The result of this paper is useful for development of the automatic spring correction system and reduction of the complicated and tedious processes involved in experimental method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.4
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• pp.90-96
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• 2016

Incremental sheet forming (ISF) is a highly versatile and flexible process for rapid manufacturing of complex sheet metal parts. Compared to conventional sheet forming processes, ISF is of a clear advantage in manufacturing small batch or customized parts. ISF needs die-less machine alone, while conventional sheet forming requires highly expensive facilities like dies, molds, and presses. This equipment takes long time to get preparation for manufacturing. However, ISF does not need the full facilities nor much cost and time. Because of the facts, ISF is continuously being used for small batch or prototyping manufacturing in current industries. However, spring-back induced in the process of incremental forming becomes a critical drawback on precision manufacturing. Since sheet metal, being a raw material for ISF, has property to resilience, spring-back would come in the case. It is the research objective to investigate how geometrical shaping parameters make effect on shape dimensional errors. In order to analyze the spring-back occurred in the process, this study experimented on Al 1015 material in the ISF. The statistical tool employed experimental design with factors. The table of orthogonal arrays of $L_8(2^7)$ are used to design the experiments and ANOVA method are employed to statistically analyze the collected data. The results of the analysis from this study shows that the type of shape and the slope of bottom are the significant, whereas the shape size, the shape height, and the side angle are not significant factors on dimensional errors. More error incurred on the pyramid than on the circular type in the experiments. The sloped bottom showed higher errors than the flat one.